土壤氮素供应状况的研究Ⅱ.硫酸铵在植稻土壤中的转化及其对土壤氮素供应状况的影响

对陈永康水稻丰产经验的研究表明,在中性水稻土上调节水稻的土壤氮素营养状况是达到丰产的关键.这就是根据土壤的氮素供应特点、因土制宜地运用肥水措施,调节水稻生长发育过程中的土壤氮素供应状况,以满足水稻器官协调生长的共同要求.     

江苏练湖农场两种主要土壤的供肥特点及其对晚稻生长的影响

两年来,从总结陈永康高产水稻施肥技术经验出发,针对水稻器官生长与土壤氮素的供求特点进行了一些工作,其目的在于探求高产水稻因土制宜的施肥原则及其科学依据.一般说来,水稻的生长中期(拔节-穗分化)是奠定壮稈大穗丰产的重要时期.在这一时期植株上有许多同时生长的器官.从已往的研究结果看来,晚稻植株的不同器官对氮素供应状况的反映不同,而同一器官在不同生育时期内影响也不一样.同时,不同土壤对氮素供应容量、强度、持续时间的贡献大小也有所不同.如何结合土壤的供肥性能和晚稻的养分需要特点,制订经济合理的施肥原则,对进一步提高产量是十分有意义的.     

镉污染水稻土中水稻氮素营养的SPAD诊断

治理和安全利用重金属污染水稻土过程中,氮素营养的快速诊断是制定合理施肥措施的基础。叶绿素测定仪SPAD已广泛应用于非污染耕地土壤中玉米、小麦和棉花等作物的氮素营养诊断,然而针对镉污染条件下的不同类型水稻土,SPAD在诊断水稻氮素营养的适应性方面仍然缺乏系统研究。本研究采集了我国水稻主产区的21种典型水稻土,以德农2000为供试水稻品种,设置无镉污染、轻度镉污染、重度镉污染处理的水稻盆栽试验,研究水稻叶片SPAD值对镉污染水稻土氮素供应诊断和水稻产量预测的能力。结果表明:水稻土类型影响了水稻叶片SPAD值对不同水平镉污染的响应,土壤p H是主控因子,其相对影响的平均值为20%。水稻叶片SPAD值与不同生育期水稻籽粒氮素含量显著正相关,其中拔节期的相关系数最大;同时水稻叶片SPAD值与水稻营养生长期(苗期至拔节期)土壤溶液总氮和铵态氮含量呈显著正相关,且不受镉污染程度和土壤类型的影响。总体上,不同生育期(尤其是拔节期)水稻叶片的SPAD值可以表征镉污染条件下不同类型水稻土氮素养分供应对水稻氮素营养的影响。     

稻草和尿素配施时水稻对肥料氮和土壤氮的吸收利用

利用＾１５Ｎ同位素示踪技术,研究了稻草和尿素配施时水稻对肥料和土壤氮的吸收。结果表明,稻草单施导致土壤速效氮的生物固定,氮素供应不足是影响水稻分蘖成穗的限制因子,稻草配合尿素施用,明显改善肥料氮和土壤氮的供应,既有利于当季水稻增产,也有利于培养土壤肥力,还有利于后茬物作产量的提高 。     

氮肥配施增效剂实现寒地水稻增产、提质与增效

研究氮肥增效剂对寒地水稻产量、品质及氮素利用的影响,旨在为制定合理的稻田氮素管理措施及增产、提质和增效策略提供科学依据。2017年和2018年在黑龙江省方正县设置田间试验,研究氮肥配施硝化抑制剂和脲酶抑制剂对水稻产量、品质、氮素利用和转化及经济收益的影响。结果表明:尿素配施硝化抑制剂CP和脲酶抑制剂NBPT(N+NI+UI)显著提高水稻产量,2017年较氮肥处理(N)水稻籽粒、秸秆和总生物量分别增产6.4%,4.9%和5.8%,2018年分别增产8.8%,7.2%和8.2%。施用氮肥增效剂可以提高寒地水稻碾磨品质、外观品质和营养品质,并促进水稻氮素吸收,提高氮肥利用效率。与N处理相比,N+NI+UI处理水稻氮肥表观利用率、氮肥农学效率和氮肥偏生产力分别提高15.6%,19.1%和7.6%。CP和NBPT配施对氮素转化表现出明显的协同抑制效果,延迟和降低土壤NH4^+—N含量峰值,保持水稻生育期较高的NH4^+—N含量,延长了氮素供应时间。施用氮肥增效剂可使寒地水稻增收2499.08元/hm^2。可见,寒地水稻氮肥配施硝化抑制剂CP与脲酶抑制剂NBPT能够延长氮素释放周期,促进水稻氮素吸收,增加水稻产量,改善水稻品质,提高氮肥利用效率,增加经济效益。     

不同氮、硅用量对水稻产量和品质的影响

硅素和氮素是水稻正常生长必需的两大营养元素.水稻氮肥的施用技术及氮肥对水稻产量和品质的影响已有大量的研究[1-5].结果表明,适宜的氮素施用量和施肥时期,可以提高抽穗期群体源库质量和群体成穗率,形成高势粒比群体而高产;氮肥施用量对水稻的品质也会产生一定的影响,但不同品种对氮素施用量的反应不同.     

氮素水平对不同氮效率基因型水稻的物质生产与分配的影响

研究了在群体水培条件下,3种氮素水平(5、15和25mg.kg-1)对6种不同氮效率利用基因型迟熟中粳水稻物质生产与分配的影响。结果表明:氮素水平、基因型对水稻氮素干物质生产效率(NUEdm)、氮素籽粒生产效率(NUEg)均有极显著的影响。6种不同氮效率基因型可分成氮高效和氮低效利用型2类。NUEdm在2类基因型水稻中总体上均随着氮素水平升高呈现上升趋势;而NUEg在氮低效基因型中表现为随氮素浓度升高而先升后降。在水稻的4个关键生育期,不同氮素水平、2类基因型之间水稻干物质积累量差异显著。成熟期,氮素水平对水稻茎鞘、根、穗的干物质分配比例影响显著,对叶片干物质分配比例影响不显著。相同氮素水平下,就平均值而言,水稻茎鞘、叶片、根系干物质比例均表现为氮低效基因型>氮高效基因型,而穗的干物质比例均表现为氮高效基因型>氮低效基因型。氮素水平对不同基因型水稻产量影响显著,同一氮素水平下均表现为氮高效型基因型水稻产量显著高于氮低效型基因型,且施氮量越大差异越大。相关分析表明,水稻各关键生育期的干物质生产量、产量、每穗粒数均与氮素水平、基因型的NUEg、NUEdm显著或极显著相关,与成熟期水稻各器官干物质分配比例相关性则相对较弱。     

水稻生长对土壤氮素矿化的影响

淹水条件下,土壤氮素的矿化是土壤有效积温的函数.用淹水密闭培养法,预测田间种稻下土壤氮素的矿化量和矿化过程时,其准确性受到许多因素的影响.为了明确水稻生长对土壤氮素矿化的影响程度,以及不同季别的水稻在这方面的异同,我们进行了下述试验.     

不同施氮处理对水稻氮素吸收及产量的影响

从水稻高效施肥的角度,通过田间小区试验,分析不同施氮肥处理对水稻氮素吸收及产量的影响。结果表明,在一定氮肥施用量范围内,水稻氮素吸收量及产量随氮肥施用量增加而提高,氮肥施用过量时,水稻氮素吸收量及产量降低;等量的氮肥(210 kg.hm-2)处理下,随着追肥次数的增加,其水稻氮素吸收量及产量也随之提高;在基肥∶分蘖肥∶穗肥∶粒肥=3∶3∶3∶1的情况下,水稻氮素吸收量及产量均达到最高水平。     

稻田干湿交替对水稻氮素利用率的影响与调控研究进展

稻田干湿交替（alternate wetting and drying,AWD）是提高水稻水、氮利用率的重要水分管理措施。水稻品种、生态环境、氮肥运筹和土壤落干强度是影响AWD下水稻氮素利用率（nitrogen use efficiency,NUE）的主要因素。AWD通过改变土壤水-气环境而影响土壤中生物化学过程,进而影响土壤氮素营养的有效性。轻度AWD促进水稻根系的生长和活力,促进水稻氮素的吸收、同化和转移而提高NUE。轻度AWD不仅提高水稻光合作用,还促进干物质向籽粒的分配,从而提高水稻产量和氮素利用率。AWD还引起植物激素的变化,植物激素也可能参与了对水稻氮素利用的调控。该文从根际氮素营养与环境、根系形态功能、氮素同化和再转移,以及碳同化和分配、植物激素调控等方面综述了 AWD对水稻氮素利用率的影响与调控,并提出了一些值得深入探讨的问题。     

应用Langmuir等温式解释我国东北某些土壤对磷酸离子的吸附作用

目前应用Langmuir吸附等温式来探讨土壤对磷酸离子的吸附作用,较为广泛.自从Olsen(1957)系统地报道以来,从机理到结合生产实际的研究已有大量的报道,我国近年来也有研究.由于土壤本身组成的复杂性,多数学者用纯物质(如纯粘土或铁与铝的含水氧化物等)进行吸附等温式的机理研究,已取得了很多结果.     

广东主要母质发育水稻土对硅的吸附特性

Silicate adsorption in eight paddy soils developed from four different parent materials in Guangdong Province, China was examined to obtain fundamental knowledge of silicate adsorption to improve the efficacy of silicate fertilizer use in these areas. A correlation analysis showed that silicate adsorption did not obey the Langmuir equation （r = -0.664- 0.301） but did obey the Freundlich and Temkin equations （P〈0.01, r = 0.885-0.990）. When the equilibrium silicate concentration （Ci） was less than 45 mg SiO2 kg^-1, the adsorption capacity was in the following decreasing order of paddy soils： basalt-derived 〉 Pearl River Delta sediment-derived 〉 granite-derived 〉 sand-shale-derived. Stepwise regression and path analysis showed that for the investigated paddy soils amorphous MnO and Al2O3 were the two most important materials that affected silicate adsorption. Moreover, as Ci increased, amorphous Al2O3 tended to play a more important role in silicate adsorption, while the effects of amorphous MnO on silicate adsorption tended to decrease.     

Soil and peach seedling responses to soluble phosphorus applied in single or multiple doses

Abstract

Two methods of measuring phosphate (P) adsorption were assessed as a means of predicting soil and plant responses to P fertigation for four British Columbia (B.C.) orchard soils. In Method 1, soils at 0.1 bar moisture tension were incubated for 1, 7, 14, 28, 56, or 84 days with solutions of H₃PO₄ supplied as a single or eight weekly doses. In Method 2, soils were equilibrated with P solutions at 1:10 soil:solution ratio for one day. Langmuir adsorption maxima calculated from the latter data ranged from 99 to 372 mg/kg. Solution P concentrations after one day for single dose incubations and 1:10 soil:solution equilibrations were highly correlated. Solution P concentrations remained elevated for 12 weeks after both single and weekly doses in incubated soils. Four availability indices were derived from the adsorption studies:solution P after one day equilibration for both methods and the fraction of the P adsorbing surface covered by added P at either one or fifty‐six days.

Peach seedlings (Prunus persica L. Batsch) were grown for 12 weeks in the greenhouse in a randomised complete block experiment with five levels of P (0, 15.5, 31, 62, and 124 mg P/kg) supplied as H₃PO₄ on the same schedule as for the incubated soils. Top dry matter increased in response to the first level of added P for three soils but was not correlated with any of four P availability indices measured. Initial soil solution P concentration was a better indicator of response to P fertilizer than Kelowna‐extractable (0.25 M HCl + 0.015 M NH₄F) P. Estimated critical values of soil solution P for the two adsorption methods were 0.85 μg/mL (Method 1) and 0.42 μg/mL (Method 2).     

Relationship between Freundlich isotherm Coefficients,log K F and 1 / n for atrazine desorption from soils in Japan

Desorption experiments were conducted on 21 soils at 3 atrazine concentrations. The Freundlich isotherm was used to estimate atrazine desorption. For the relationship between Freundlich isotherm coefficients, log K _F and 1 / n, 1 / n was also represented by a linear regression of log K _F as in the case of atrazine adsorption. All the linear regression lines of desorption exhibited larger slopes and intercepts than those of adsorption. When the atrazine concentration was high, the slope and intercept values were smaller than those for the desorption regression lines. The results showed that the larger the capacity of a soil to adsorb atrazine, the lesser the amount of atrazine desorbed. For the cultivated soils except for Andisols, the percentages of atrazine taken from solutions using the sequential exchange method after the first adsorption experiments, were the same as those desorbed from soils in relation to the initial amount adsorbed. Thus, reversible adsorption occurred in the soils due to weak physical adsorption.     

Adsorption and desorption of organotin compounds in organic and mineral soils

Organotin compounds (OTC) are deposited from the atmosphere into terrestrial ecosystems and can accumulate in soils. We studied the adsorption and desorption of methyltin and butyltin compounds in organic and mineral soils in batch experiments. The adsorption and desorption isotherms for all species and soils were linear over the concentration range of 10–100 ng Sn ml^?1. The strength of OTC adsorption correlated well with the carbon content and cation exchange capacity of the soil and was in the order mono‐ > di‐ > tri‐substituted OTCs and butyltin > methyltin compounds. The OTC adsorption coefficients were much larger in organic soils (K_d > 10⁴) than in mineral soils. The adsorption and desorption showed a pronounced hysteresis. Trimethyltin adsorption was partly reversible in all soils (desorption 2–12% of the adsorbed amounts). Dimethyltin, tributyltin and dibutyltin exhibited reversible adsorption only in mineral soils (desorption 4–33% of the adsorbed amounts). Mono‐substituted OTCs adsorbed almost irreversibly in all soils (desorption < 1% of adsorbed amounts). Trimethyltin was more mobile and more bioavailable in soils than other OTCs. It might therefore be leached from soils and accumulate in aquatic ecosystems. The other OTCs are scarcely mobile and are strongly retained in soils.     

Adsorption of radiocaesium on various soils: consequences of the effects of soil: solution composition on the distribution coefficient

The adsorption of a radioisotope of caesium, ¹³⁷Cs, has been interpretation and ratio and solution measured on four soils with differing clay mineralogies. All measurements have been made using unwashed soils in suspensions shaken for 2 h at 20°C. The effects of concentration in potassium and caesium, the nature of the background electrolyte and the soil:solution ratio have been investigated. The results are expressed either as the distribution coefficient, K_D or as Freundlich isotherms. The distribution coefficient of each of the soils decreases markedly as the concentration of caesium increases. The adsorption properties of the soils are not determined by the dominant clay mineralogy alone. Adsorption is always lower in 0.01 m CaCl₂ solution than in water. The addition of potassium has relatively little effect on adsorption of trace amounts of caesium; however, K_D decreases with increasing concentrations of stable caesium. The major reason for the dependence of K_D on the soil: solution ratio is found to be the non-linear adsorption isotherm; the influence of the varying compositions of the solution and exchange complex is minor. The validity of the use of a single K_D value as an indicator of adsorption capacity and the meaning of the relative values of the Freundlich parameters are considered. The implications of these findings for the use of radiotracers and the usefulness of K_D as an indicator of bioavailability are discussed.     

THE HIGH- AND LOW-ENERGY PHOSPHATE ADSORBING SURFACES IN CALCAREOUS SOILS

The two-surface Langmuir equation was used to study P adsorption by 24 calcareous soils (pH 7.2-7.6; 0.8-24.2 per cent CaCO₃) from the Sherborne soil series, which are derived from Jurassic limestone. High-energy P adsorption capacities (x″_m) ranged from 140–345 μg P/g and were most closely correlated with dithionite-soluble Fe. Hydrous oxides therefore appear to provide the principal sites, even in calcareous soils, on which P is strongly adsorbed (x″_m 6–51 ml/μg P). The low-energy adsorption capacities (x″_m) ranged from 400–663 μg P/g and were correlated with organic matter contents and the total surface areas of CaCO₃ but not with per cent CaCO₃, pH, or dithionite-soluble Fe. Total surface areas of CaCO₃ in the soils ranged from 4.0 to 8.5 m²/g soil. Low-energy P adsorption capacities agree reasonably with values (100 pg P/m²) for the sorption of phosphate on Jurassic limestones but phosphate was bonded much less strongly by soil carbonates (k″= 0.08–0.45 ml/μg P) than by limestones (k～10.0 ml/μg P). Low-energy P adsorption in these soils is tentatively ascribed to adsorption on sites already occupied by organic anions (and probably also by bicarbonate and silicate ions) which lessen the bonding energy of co-adsorbed P.     

Verification of the prediction technique for the amount of adsorbed linuron on soils

The Freundlich isotherm was used to estimate the adsorption of the herbicide linuron on 39 Japanese soils to confirm the suitability of the prediction technique used in atrazine adsorption. Linuron was adsorbed on the soils according to the Freundlich isotherm. In conjunction with the log K _F prediction equation derived from the soil characteristics, it was possible to predict the linuron adsorption. Comparison of the equations for linuron with those for atrazine, indicated that the difference in the intercept of the 1 / n regression line against log K _F reflected the adsorptive characteristics of the herbicides.     

土壤吸附砷酸盐动力学的初步研究

本研究目的是了解陕西省的几种土壤吸附和解吸附砷酸盐的速率和过程,以及其吸附能量。Kuo和Lotse导出的双常数速率公式拟合试验资料优于一级、二级、三级反应公式,抛物线扩散和Elovich公式等五个公式。用双常数速率公式(C=k·C₀·t^1/m)分两段拟合能进一步提高拟合优度。根据Arrhenius公式计算出的吸附活化能是0.70—3.40千卡/克分子。低的活化能表明,供试土壤对砷酸盐的吸附作用是一种完全不同于真溶液条件化学反应的物理学过程。土壤吸附和解吸附砷酸盐的速度和容量受作用时间、温度、溶液∶土壤比率,加入的砷量和浓度,以及土壤特性的影响。粘土的吸附反应常数(k),吸附量比沙壤土大。而沙壤土有高的解吸附反应速度常数(k_-1^'),砷酸盐容易被解吸附而释放出来。     

A LANGMUIR TWO-SURFACE EQUATION AS A MODEL FOR PHOSPHATE ADSORPTION BY SOILS

For forty-one soils (pH > 5.0) from southern England and eastern Australia, the Langmuir equation was an excellent model for describing P adsorption from solutions < 10^-3M P, if it was assumed that adsorption occurs on two types of surface of contrasting bonding energies. For most of these soils, which were relatively undersaturated with P, this equation may be written as: where x = adsorption, k = adsorption/desorption equilibrium constant, x_m= monolayer adsorption capacity, and c = equilibrium solution concentration. The relative magnitude of the parameters for each surface were approximately: x_m= 0.3 x^″_m=0.3 and k′= 100 k. More than 90 per cent of the native adsorbed P occurs on the high-energy surface in most soils.